Milling machine control gear



Oct. 5, 1948. J, FRYE MILLING MACHINE CONTROL GEAR 4 Sheets-Sheet 1 Filed Aug. 15, 1945 Oct. 5, 1948.

J. FRYE.

MILLING MACHINE CONTROL GEAR 4 sheetsesheet 2 Filed Aug. 13, 1945 [5. fair 920 v ZfcS 2/65 PS 2 l EMS M50/& 0 2

Attorney Oct. 5, 1948. FRYE v MILLING MACHINE CONTROL GEAR 4 Sheets-Sheet 3 Filed Aug. 15, 1945 FIGS.

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Invenlpr JACK FRYE y B v Altorney Oct. 5, 1948. FRYE MILLING MACHINE CONTROL GEAR 4 Sheets-Sheet 4 Filed Aug. 13, 1945 .m I t 9m. w. a! La Will! 55 8 5 running Inventor .TAC K FR YE y Attorney Patented Oct. 5, 1948 4 MILLING MACHINE CONTROL GEAR Jack Frye, Broomfield, Abbotts Langley, England Application August 13, 1945, Serial No. 610,575 In Great Britain December 3, 1943 Section 1, Public Law 690, August 8, 1946 Patent expires December 3, 1963 13 Claims.

The present invention relates to milling machines, and refers more particularly to milling machines of the knee type, in which a knee projects forwardly from the standard beneath the milling spindle, and carries a work table which can be horizontally traversed in either of two directions at right angles, namely parallel to, and at right angles to the milling spindle. The work table can also be raised and lowered by vertically traversing the knee either upwardly or downwardly on the standard.

The object of the invention is to provide improved means for controlling the operation of the machine, viz. the rotation. of the milling spindle and the traversing of the work table and knee, the controlling means being in part mechanical and in part electrical, whereby the operation and control of the machine is facilitated and simplified.

The machine is operated by two electric motors, one for driving the milling spindle in either direction, and another of smaller power adapted to be selectively operated to drive the vertical knee traversing gear, or either of the two horizontal table traversing gears, in either direction 1. e. backwards and forwards, or transversely left or right. The control gear also permits various combinations of these traversing movements with the spindle movement to be obtained simultane ously. Furthermore the traversing gears are adapted to be selectively operated at either slow or high speed, the former speed being generally utilised for cutting operations and the latter for return movements of the work table, when no cutting operation is in progress.

The mechanical gear for operating the milling spindle may comprise simply a speed reducing gear box interposed between the larger driving motor, which is of reversible type, and the milling spindle, the drive from motor to gear box being through a belt and pulleys.

The mechanical gear for traversing the knee vertically and the work table horizontally backwards and forwards or transversely on the knee comprises a reduction gear train driven by a small reversible electric motor which drives a shaft carrying a sliding pinion which can be brought by a selection lever into mesh with any one of three pinions, one pinion driving a screw adapted to traverse the work tablebackwards and forwards on the knee, another pinion driving a screw adapted to traverse the work table on the knee transversely to the milling spindle, and the third pinion driving a screw adapted to traverse the knee carrying the table vertically.

The said shaft is driven at a fast or slow speed through a two way clutch, the moving member of which is operated by a clutch control lever to clutch the shaft direct to the final element of the reduction gear train driven by the motor, to give a high speed of traverse, or to a speed reduction gear box driven by an intermediate member of the reduction gear train, to give a low speed of traverse.

In accordance with the foregoing, therefore, the improved milling machine driving and control gear according to the invention comprises an electric motor fordriving the milling spindle in either direction through speed reduction gearing, a second motor adapted to drive ashaft adapted to be selectively coupled to means for varying the height of the work table. its position in a horizontal direction parallel to the milling spindle, or its position in a horizontal direction at right angles to the milling spindle, and means for varying the speed at which said shaft is driven by said second motor operating at a given speed. Thus in one arrangement said shaft is adapted to be coupled directly through a gear train to the second motor, or indirectly through a speed reduction gear box to the same gear train.

An important part of the invention resides in the electrical control gear for the two motors, which are not separately controlled but jointly controlled in functional co-operation. Further in certain respects the electrical control gear is functionallycombined with the mechanical control gear.

Thus according to a further feature of the invention the driving and control gear comprises an electric motor for driving the milling spindle in either direction, a second motor for traversing the knee carrying the work table up or down or traversing the table on the knee, either left or right, or backwards or forwards, switch means for selectively controlling the direction of traverse, and means associated with said switch means for selectively controlling the speed of traverse to give a slow or a quick traverse at will. Furthermore said switch means may also control the spindle motor in such manner as to set it running before the traverse motor is set running, in moving from a neutral stop position into traversing position.

According to another feature of the invention the electrical control gear includes a spindle selector switch, whereby the spindle may be'caused to run in either direction of traverse, but not in the reverse direction, or to run in both directions of traverse.

.control arrangements.

The invention also includes certain features in relation to the braking of the spindle and traversing motors, which is eflected electrically by current injected into the windings of the traversing and spindle motors. Thus according to this part of the invention the control gear includes means which are automatically rendered operative on the switching off of the traversing or spindle motor to apply a braking action to the motor concerned.

The machine may be operated electrically by direct current, or' by alternating current,- in which case three-phase A. C. is preferred. In the case, however, of alternating-current.operation of the two driving motors, braking of these motors is effected by the injection of direct current into their windings, the direct-currentbeing obtained from the alternating current supply through a rectifier. Means may be providedfor varying the braking current to control the brak- In order. that the invention. may be'cle'arly understood and readilycarried into practice, it

. is illustrated, by way of. example only, in the ac- 'chine according to the invention,

Figure 2 is a diagram illstrating the functions of the spindle and feed control starting switch, Figure 3 is a diagram illustrating the func- :tions of the spindle selector switch, and

" Figure 4 is a circuit diagram of theelectrical Figures 5 and 5A are enlarged diagrams cor- .responding to the diagram of Figure 4.

vAs previously indicated: the machine isoperated by two motors, one of which is adapted to by shaft 32 operating at a higher speed.

In Figure 1 the gear 25 on shaft 32 is shown meshed. with gear 27 driving traversing screw 33, givingforward and backward movement of the Work table 29 on the knee of the machine. If gear 25 is meshed with gear 28 it drives through bevel gearing 38, 39, a traversing screw 40 giving vertical movement to the knee carrying the .table 29, whilst if it is meshed with gear 26, a

. traversing screw 4| drives the work table 29 to left or right in thehorizontal direction, through bevel gearing 34, 35, 36, 31.

The adjustment of gear into mesh with any rection of traverse is effected-,as; diagrammatically indicated, by lever 30, which; accordingly has three setting positions.

"23, 24, a main switch [controlling-the; spindle motor and the traverse or feed motor S ashereinafter described, and a rockingmovement which operates clutch 19. I The? various; setting positions of lever 22are indicated:in-gFigure 2. In positions a the spindle motor isstarted running in a direction determined by switch' ,lS-.(Figure l),- inpositions b the traversinggmotor; is-;operated-to traverse in one direction orthe other,

either up or down,; leftor right or'forwards or backwards, according to the setting of the-traverse selector lever 30, whilst in either; end position b the lever 22 can be rocked forwardly to operate clutch l9 to give a quick" return traverse.

ing illustration. The other motor. is of smaller power and is used for selectively traversing the .work table in any of. six directions; viz. horizon- ..tally ineither direction on the knee, vertically in either direction with the knee,.and.backwards and forwards on the knee.

The invention is. mainly concerned with the electrical control gear of the machineand its association with the mechanical operating gear 'of the machine, but the mechanical arrange- 1 .ments will first be briefly. described.

The spindle is driven through normal reduction gearing by a. reversible electric motor controlled by normal electrical switch gear. In Figure 1, therefore, onlythe mechanical arrangements for the traversing motor are diagrammatically shown.

Referring now to Figure 1, 9 indicates the traversing motor,.which drives through reduction gearing ll, l3 and bevelgearing l4, [5, a shaft 3|, which drives through bevel-gearing l6, l7,

. the input side of a reduction gear box I0, the output side of which drives, through chain or cording to the adjustment of the clutch IS the I shaft 32 is driven by motor 9 either through gear train II, l3, I2, 20, 2| at a high speed, or. through The electrical control equipment for the-machine in the case of a threeephase :supply,--system is illustrated by Figures 3, 4,-5 and 5A, all the switches being shown inthe positions they-pccupy when the machine is: shut ,down.

the connections tothe lines, of two of the threephase windings of the-spindle-motor; SW-itchZS is a'simple make-and break-switch of conyentional construction provided as ,athe main -.control switch I of Figure 2-;for starting andstop- ;ping the spindle motor anditliaversing motor 9,

and also for selecting the direction ef-running --of .the traverse motor. and its-speedjQf running,

as will-hereinafter-appear. Switch- 4S, is -the spindle selectorswitch; which is provided to determine in which direction of traverse the spindle runs, whether itruns in ;bothdir.ections of for feeding a cooling-andlubricating-fluid;tothe milling tool and work.

;-In addition there is a normally; closed- -=.master stop-"-switch MS ofpush buttonrtype, whichcan be operated at anytime to stop the whole machine working,-for closing-down. This islocated in a convenient position. for.,the.:operat0r.workingthe, machine, and is' duplicatedby one or more remote master. stop? switches RMS located at some other convenient position or positions at which the master switch MS is not accessible to the operator. There is also a prepare start" switch PS which is open when the machine is closed down and is manually closed prior to starting, for the purpose of energising the operating coil 4CI of contactor 40 to operate switch 401 which makes the circuits of the operating coils IcI, 2fcI and 2rcI of'the' three main contactors IC, 2FC and ZRC ready for completion by main control switch 2S. After manual operation of switch PS the contactor 4C is held closed by a maintaining circuit through 403, until the circuit of contactor operating coil 4cI is broken by operation of the master stop switch MS or the remote master stop RMS. The three switches MS, EMS and PS are in series with operating coil 4CI across the lines L1, L3.

The power supply lines L1, L2, In are adapted to be connected by triple pole contactor IC operated by coil ICI, through thermal overload trip coils ITT and a reversing switch IS to the spindle motor, which is connected at IA, IB, IC. The switch IS in one position supplies current from line L1 to phase winding IA, along path 56, 58, and to phase winding IB from line L2 along path 51, 59, whilst in the reverse position of the switch the connections of these two windings are reversed, so that winding IA is fed through path 51, 58 and winding IB is fed through path 55, 59.

The lines L1, L2, L3 also feed two triple pole contactors 2FC, 2RC operated respectively by coils Mel and 2rcI, for producing forward and reverse running respectively of the traversing or feed motor 9, the triple pole starter switch 38 supplying at terminals 3A, 3B, 3C a small auxiliary motor for operating a pump supplying suds to the milling tool and work, and a double pole contactor 4C for energising a tapped auto-transformer T'which supplies the braking current as hereinafter explained.

The circuits between contactors 2FC and 2R0 and the traverse motor 9 include thermal overload trip coils 2TT, and the circuit between transformer T and braking rectifier I /2R includes a thermal overload trip coil I /2RTT. The three thermal overload switches operated by these trip coils, namely Itt for spindle motor, 21ft for the traverse motor 9, and I/Zrtt for the rectifier are in series with the master stop switch MS, through which the main control switch 28 is supplied.

When prepare start switch PS is closed the circuit of braking contactor operating coil 4c| is closed through path 02, Ol, MS, 03, RMS, 14, Itt, I3, I/2rtt and 21ft, and switches 403 and 4c! become closed. Closure of switch 403 completes a maintaining circuit for operating coil 4cI. Closure of switch 401 makes the circuits of operating coil ICI of spindle motor contactor, of operating coil 2fcI of forward contactor ZFC, and of operating coil 2rcI of reverse contactor 2R0 of the traverse motor 9, through interlocking switch Ibc4 of spindle motor brake contactor IBC, limit switches VLS, LLS, TLS' and interlocking switches 2]04 of forward traverse contactor ZFC and 2rc4 of reverse traverse contactor 2R0, ready for completion by switch 28 according to its direction of movement, either to bridge contacts 50, 52, 54 or contacts 49, 53.

traverse motor is stationary. In one of these positions the switch 23 bridges contacts 49, 53

and in the other position bridges contacts 50-54, and since the contacts 49, 53 and 50, 54 are in parallel circuits in series with contactor coil ICI, the spindle runs in both cases, in a direction determined by switch IS. If the switch lever 22 (Fig. 2) is moved further over in either direction into position b, b, the traverse motor is also brought into action to feed either forward or back, as the result of switch 28 bridging either contact 5| in addition to 49-53 or contact 52 in addition to 50, 54. In positions b, b the traverse produced by motor 9 will take place either slowly or fast according as switch lever 22 remains upright or is pulled forwardly as previously explained; the slow speed is used during cutting traverse or feeds and the high speed for return traverses.

However, before switch 28 moves fully over to bridge contacts 49, 5I or contacts 50, 52, as the case may be, it bridges contacts 49, 53, or 55), 54, thereby completing the circuit of the operating coil ICI of spindle motor contactor IC, through selector switch 4S, the setting of which to make a path through 53, 55 or 54, 55 determines the direction of running of the spindle motor.

Switch 2S is the rotary switch I driven by gearing 23, 24 from the spindle of lever 22 in Figs. 1 and 2. In positions b of lever 22, switch 25 is set to complete the circuit of either the operating coil Zfcl of forward contactor 2FC or the operating coil ZrcI of reverse contactor 2R0 of the traverse motor. At the same time the circuit of operating coil IcI of spindle motor contactor IC is also completed. In positions a, however, of lever 22, the circuit of operating coil iCI of spindle motor contactor 10 only is completed.

, As will be seen, there are two series of limit switches VLS, LLS and TLS located in position to be tripped bythe work table at opposite ends of its travel, VLS indicating the vertical limit switches, LLS the longitudinal limit switches, and TLS the traverse limit switches. These sets of switches are in series with the operating coil 2fcI or MOI of the contactor ZFC or ZRC which is operative in producing the direction of trav erse at the end of which the limit switch becomes operative.

The spindle selector switch 48 a simple make and break switch of conventional construction is a rotary switch operated by lever 44 having the four positions indicated in Figure 3. In the vertical upright or off position the paths 53-55 and 54-55 of Figure 4 are both broken and the spindle motor remains stationary; in the vertical downward position both of said paths are completed and the spindle runs during both directions of traverse; in the right hand side position the spindle runs when the table traverses right, due to completion of path 53, 55, whilst in the left hand side position path 54-55 is completed and the spindle runs when the table traverses left.

Also connected across the lines L1, L2 in parallel with the above switch gear is a circuit through the operating coil IbcI of the brake con tactor IBC for the spindle motor. This circuit is interlocked with the spindle motor contactor IC by the normally closed switch IC5 which energises operating coil Ibcl, when the spindle contactor IC opens. It is also controlled by the normally open switch ISR, which is closed by a slugged relay Isrl immediately upon the completion of the circuit of the coil IsrI, by closure of switch I05 on operation of the spindle motor contactor IC,, and opens after a predetermined time delay following opening of contactor IC.

Thusthe closure of spindle contactor 10 completes thecircuit of slugged relay coil lsrl at switch I05, and causes closure of switch lSR. However, when contact EC is opened the switch lSR does not immediately open, but only Opens after a predetermined time delay. During this time delay the contactor NBC is operated by coil lbcl' and injection of D. G. into the spindle motor takes place, to produce braking as hereinafter described.

Similarly there is another parallel circuit through the operating coil 21ml of the braking contactor 2130 for the traversing motor, which is completed by closure of switch ZSR by slugged relay 2srl, immediately upon the closure of' switch 2jc5 or 21-05, by the forward contactor 2FC or the reverse contactor 2R0, which completes the circuit of slugged relay 2srl1 This cirsuit is interlocked with the traverse motor for ward and reverse contactors 2FC and 211C respectively by the normally closed switches 211: and 2706 respectively, which de-energize the traverse motor brake contactor operating coil Zbcl, when either of them is opened by operation of the forward or reverse running contactor as the case may be.

The slugged relay 237-! opens theswitch ZSR only after-a predetermined time interval following deenergisation of relay coil Zsri at contacts 2 05, Zjcfi opened by opening the main contactor Z'FC or 2R0, and it is during this time interval that. contactor 2130 is operated by coil 2bci to cause injection of D. C. into the traversing motor and braking occurs as hereinafter explained.

The spindle and traverse motors are both braked by' injecting direct current into their windings under the control of suitable switch gear. The direct current is obtained from a selenium rectifier I /2B which is supplied at points ii Si by a tapped auto-transformer T fed from mains L2, L3 through contactor 4C, thermal overload trip coil l /2 R. T. T., and through the middle pole of either the spindle motor braking contactor IE0, or the traverse motor braking contactor 230, and terminal 12 of voltage changing switch VC, whose contactors 6d and 65 are connected to tappings at different voltages on transformer T. In the case of the traverse motor a resistance 2p is provided in the circuit to reduce the braking current. Points 62, 63 of the rectifier supply the spindle and traverse motors respective ly through two of the poles of the respective con 'tactors i130 and 2B0. The switch VC permits of a degree of adjustment of the braking current.

A further supply of direct current is obtained fromtapping points on transformer T for. application to the slugged timing relay operating coils isrl and Zsrl. A low voltage, say 50 volts is fed from thetransformer TV to input terminals [38, 69 of selenium rectifier 4B, and the output terminals Ti] and H of the rectifier are connected to the relays Isrl and 2srl in parallel, the connections from terminal ll passing through switch 805 of forward spindle contactor IC in the case of relay isrl, and either through switch 2;05 of traverse motor forward contactor 2FC, or switch 2rc5' of traverse. motor reverse contactor 2R0 in the case of relay Zsrl.

Energisation of relay coil Isrl causesclosure of relay switch ISR after a predetermined time interval following closure of brake contactor 4G, to energise. spindle. brake contactor coil lbcl, and similarlyenergisation of relay coil 2srl will after a predetermined time interval energi'sei the operating coil :2bcl of traverse motor braking contactor 2B6, through switch 28R.

Itwill be seen thatthe circuit of spindlemotor braking contactor ibcl becomes energised when the spindle motor contactor IC is opened, in which position :switch 106- is closed, as the result of closure of switch ISR, after a suitable time interval, byslugged relay lsrl whose circuit is completedxby switch iC5,.c1osed when contactor lC opens. 'Similarly the circuit of traverse motor braking contactor Zbcil becomes energised when the spindlemotor forward contactor ZFC, or the reversecontactor. ZRC is opened, in which cases switches 2 06, and Zrcli are both closed as the resultof closure of switch 23R, after a suitable time: interval, by slugged relay 2srl, whose circuit is completed by contactor. 2 05 or 2rc5 when contactor 2FC or 2R0, as the case may be, opens.

Obviously many modifications-may be made in the arrangements and circuits herein described and illustrated without departing from the scope of the invention as hereinafter defined.

I claim:

1. Milling machine driving and control gear comprising a driving motor for the milling spindle, a reversing. switch'for selectively controlling the direction of running of said motor, a second electric motor for adjustingthe work table of the machine, a shaft adapted to be driven by said motor at high or low speed according to the setting of a control member, means for selectively coupling said shaft to driving means for raising and lowering the work table, or traversing the work table laterally, or moving the work'table to and fro parallel to the milling spindle, and a common control switch for both of said motors having a neutral position in which-both motors are at rest, two extreme lateral positions in which the spindle motor and the second motor run'in opposite directions to traverse the table in opposite directions, and two other lateral positions intermediate between the neutral position and the extreme lateral positions in which the second motor does not run but the spindle motor runs, so that traverse of the work is stopped before the milling cutter ceases to rotate.

2. wlling machine driving and control gear comprising a driving motor for the milling spindle, areversing switch for selectively controlling the direction of running of said motor, a second electric motor for adjusting the work table, a shaft adapted to be driven by said motor at high or low speed according to the setting of a control member, means for selectively coupling said shaft to driving means for raising and lowering the work table, or traversing the work table laterally, or moving the work table to and fro parallel to the milling spindle, and a common control switch for both of said motors, :whose operating member has a neutral position in which both motors are at rest, two extreme lateral positions in which the spindle motor runs and the second motor runs in opposite directions to traverse the table in opposite directions, said operating member constituting the aforesaid control member and being movable in said extreme positions to give fast or slow drive of the table traversing gear by the second motor, and said operating member has two other lateral positions intermediate between the neutral position and the extreme lateral positions in which the second motor does not run but the spindle motor runs, so that traverse of the work is stopped before the milling cutter ceases to rotate.

3. Milling machine driving and control gear comprising a driving motor for the milling spindle, a reversing switch for selectively controlling the direction of running of said motor, a second electric motor for adjusting the work table, a shaft adapted to be driven by said motor at high or low speed according to the setting of a control member, means for selectively coupling said shaft to driving means for raising and lowering the work table, or traversing the work table laterally, or moving the work table to and fro parallel to the milling spindle, and a spindle selector switch whose operating member has four setting positions in one of which the spindle motor is stopped, in another of which the spindle motor is caused to operate in the direction of traverse only, in the third of which the spindle motor is caused to operate in the other direction of traverse only, and in the fourth of which the spindle motor is caused to operate in either direction of traverse, said spindle selector switch operating in conjunction and in series with a control switch the setting of which determines the direction of running of the second motor according to the desired direction of traverse.

4. Milling machine driving and control gear according to claim 1, including a spindle selector switch, whereby the spindle may be caused to run in either direction of traverse but not in the reverse direction, or to run in both directions of traverse.

5. Milling machine driving and control gear according to claim 1, including means which are automatically rendered operative on the switching off of the traversing or spindle motor to apply a braking action to the motor concerned for a predetermined time interval.

6. Milling machine driving and control gear according to claim 2, wherein the braking is effected electrically by current injected into the windings of the traversing and spindle motors.

7. Milling machine driving and control gear according to claim 2, wherein the traversing and spindle motors are operated by alternating current, but for braking purposes direct current is injected into their windings.

8. Milling machine driving and control gear according to claim 3, including means for varying the strength of the braking current applied to the traversing and spindle motors.

9. Milling machine driving and control gear according to claim 1, comprising a main switch adapted to control the running of the spindle motor and also to control the direction of running of the traverse motor, a switch controlling the direction of running of the spindle motor, and a selector switch the setting of which causes the spindle motor to run in either of the two directions of traverse and to remain stationary in the other direction of traverse, or prevents the spindle motor from running, or causes the spindle motor to run in both directions of traverse.

l0. Milling machine driving and control gear according to claim 2, wherein a lever operating the main switch is also operable in either of its two positions producin running of the traverse motor in one direction or the other, to control clutch shifting means whereby the traverse motor is driven at either one of two different speeds.

l1. Milling machine driving and control gear according to claim 3, including limit switches adapted to be tripped by a predetermined movement of the work table, to interrupt the circuit controlled by the main operating control switch controlling the operation of the traversing motor.

12. Millin machine driving and control gear according to claim 2, including a normally closed master stop switch, and one or more remote master stop switches, in series with an operating coil which sets switches to prepare the circuits of forward and reverse contacts for the feed motor, for completion by the main operating control switch.

13. Milling machine driving and control gear according to claim 3, including a prepare start switch in series with the master stop and remote master stop switches, which is open when the machine is shut down and is manually closed to enable the motor conta'ctors to be operated by the main operating control switch.

JACK FRYE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

